Technical Field
The present application generally relates to semiconductor devices, and more particularly to semiconductor proximity sensor devices.
Description of the Related Art
FIG. 1A is a top plan view of a conventional proximity sensor 100. The proximity sensor 100 includes a cap 102 having a first aperture 104 and a second aperture 106 formed therein. FIG. 1B is a cross-sectional view of the proximity sensor 100 along the line IB-IB shown in FIG. 1A. The proximity sensor 100 includes a light emitting device 108 and a semiconductor die 110 disposed on a printed circuit board substrate 112. A sensor area 114 is disposed on an upper surface of the semiconductor die 110. A lens 116 is secured to the semiconductor die 110 above the sensor area 114 using a transparent adhesive material 118. Alternatively, a pair of the lenses 116 may be secured to the cap 102 using an adhesive such that light passing through the first aperture 104 and the second aperture 106 also passes through the lenses 116. The light emitting device 108 emits light through the first aperture 104. The light emitted by the light emitting device 108 that is reflected by an object in the vicinity of the proximity sensor 100 may enter the second aperture 106, travel through the lens 116, and impact the sensor area 114. The proximity sensor 100 outputs a signal indicative of the intensity of light that is incident on the sensor area 114.
As shown in FIG. 1B, the cap 102 includes a first cap piece 102a, a second cap piece 102b, and a third cap piece 102c. The cap pieces 102a-102c are extremely small, generally having dimensions between 15 micrometers and 150 micrometers. The first cap piece 102a is secured to the printed circuit board substrate 112 using an adhesive material 120a. The second cap piece 102b is secured to the semiconductor die 110 using an adhesive material 120b. The third cap piece 102c is secured to the printed circuit board substrate 112 using an adhesive material 120c. 
During fabrication of the proximity sensor 100, the adhesive material 120a and the adhesive material 120c are deposited on an upper surface of the printed circuit board substrate 112, and the adhesive material 120b is deposited on an upper surface of the semiconductor die 110. The tiny cap pieces 102a-102c are carefully positioned on the adhesive materials 120a-120c, respectively. If the cap pieces 102a-102c and/or the adhesive materials 120a-120c are not precisely placed in their intended locations, the cap pieces 102a-102c may not adhere properly and/or may not form the apertures 104 and 106 over the light emitting device 108 and the sensor area 114, respectively. Thus, fabrication of the proximity sensor 100 may result in a high defect rate, which can increase manufacturing costs.
Accordingly, proximity sensor devices that can be fabricated with lower defect rates are needed.